Replaceable welding tip for vibratory welding apparatus

ABSTRACT

A replaceable welding tip for a vibratory high frequency welding apparatus comprises a sleeve having a plurality of ridges, each ridge including a workpiece engaging surface. The tip is clamp mounted by screw means to an antinodal region of the resonator which provides the vibratory energy to the tip. The axis of vibration of the workpiece engaging surfaces and that of the thread of the screw means are substantially parallel with each other.

tlrtite tates Patent [191 Holze, Jr. et a1.

[ May 28, 1974 REPLACEABLE WELDING T11 FOR VIBRATORY WELDING APPARATUSInventors: Ernest P. Holze, Jr., Brewster, N.Y.;

Donald R. Culp, Danbury, Conn.

Assignee: Branson Instruments, Incorporated,

Stamford, Conn.

Filed: Feb. 2, 1973 Appl. No.: 329,092

US. Cl 228/1, 29/4701, 156/73 Int. Cl 823k 5/20 Field of Search 228/1;29/470.1; 156/73,

References Cited UNITED STATES PATENTS Jones 228/1 X Balamuth et al228/1 X 5/1965 Maropis 29/470 3,426,951 2/1969 Pohlman et al 29/4701 X3,752,380 8/1973 Shoh 156/73 X Primary Examiner.l. Spencer OverholserAssistant Examiner-Robert .1. Craig Attorney, Agent, or Firm-Ervin B.Steinberg [5 7 ABSTRACT A replaceable welding tip for a vibratory highfrequency welding apparatus comprises a sleeve having a plurality ofridges, each ridge including a workpiece engaging surface. The tip isclamp mounted by screw means toan antinodal region of the resonatorwhich provides the vibratory energy to the tip. The axis of vibration ofthe workpiece engaging surfaces and that of the thread of the screwmeans are substantially parallel with each other.

11 Claims, 6 Drawing Figures mamznmz m4 3.8131106 SHEEI 1 0F 2 F G. 1(Prior Art) GENERATOR a;

n l I F G 2 (Prior Art) PATENTEDumBmM 3.813.006

SHEET 2 0F 2 FIG. 3

GENERATOR REPLACEABLE WELDING TIP FOR VIBRATORY WELDING APPARATUS BRIEFDESCRIPTION OF PRIOR ART This invention refers to welding apparatus asdisclosed in US. Pat. Nos. 2,946,l19 and 2,946,120 which revealvibratory welding of metal workpieces, the weld achieved being in theform of a non-fusion bond. The method and apparatus to accomplish thejoining of metal workpieces comprise means for holding the workpieces tobe joined in intimate contact under a static force and applying to oneof the workpieces vibratory energy in a direction substantiallyperpendicular to the direction of the applied force. The vibratoryenergy used may be in the sonic or in the ultrasonic frequency range andpreferably is between and 100 KHz.

More specifically, this invention concerns an improved welding tipconstruction which applies the vibratory energy generated to the metalworkpiece and the attachment of the tip to the resonator forming a partof the welding apparatus.

It will be apparent that the tip transferring vibratory energy to theworkpiece is subject to wear due to the combination of pressure and highfrequency vibration. Hence. as the welding apparatus is operated inproduction, the tip must be replaced in the same manner as an ordinarymachining tool bit or an electrical welding electrode requires frequentdressing and replacement. In the past replaceable tool tips forvibratory welding apparatus have been designed and are shown forinstance in US. Pat. No. 3,038,358, I. B. Jones, dated June 12, l962 orin pending application for US. Pat. Ser. No. 234,198 filed Mar. 13, l972in the name of Andrew Shoh, entitled Vibratory Apparatus, whichapplication is assigned to the assignee of this application. However,these prior constructions have been only moderately successful anddifficulty in terms of reliability has been experienced when theapparatus were used as a production tool. Some of the shortcomings ofthe prior art designs may be summarized briefly as follows:

The threaded tip joint design of prior art constructions does notutilize maximum thread strength under vibration. Specifically, thethread axis is generally perpendicular to the axis of vibration, andhence, the thread is stressed in a radial direction instead of an axialdirection in which a threaded joint exhibits maximum strength. Therocking of the tool tip causes wear on the sides of the thread (radialdistance between root and outer diameter) and is responsible for aprogressive deterioration of the thread and joint. The prior methods ofattachment of the tool tip to either the resonator or the vibrationtransmitting member have not been adequate to handle tool tipsincorporating comparatively large workpiece engaging surfaces. Some ofthe prior constructions require accurate radial orientation of theresonator to which the tip is attached so that the workpiece engagingtip will contact the workpiece at the proper angle. Certain priordesigns, furthermore, cause an axially asymmetrical load on theresonator. Similarly, several of the previous constructions provide onlya relatively small clamping area in relation to the size of theworkpiece engaging tip surface and incorporate non-planar clampingsurfaces which are difficult to machine and to mate with complementarysurfaces.

The requirement for a good tip design involves inter alia the followingconsiderations:

Since the workpiece engaging surface of the tip is subject to wear withusage, the tip not only must be replaceable, but the replacementprocedure must be simple and must be capable of being carried out byinexperienced personnel. The method of attachment of the tip and itsworkpiece engaging surface to the resonator must be adequate for highvibrational amplitude operation without power loss in the joint. Heatingat the joint is indicative of power loss and of mechanical motion whichmay result in inconsistent welding and lead to a gradual deteriorationof the joint itself. The workpiece engaging surface of the tip shouldoffer a choice of configurations and cross-sectional shapes. The tipdesign must lend itself to the use of large cross-sectional workpieceengaging surfaces. Also, the tip construction should be such as not torequire critical resonator alignment, thereby facilitating the use ofdifferent resonators with different gains and amplitudes as may berequired to provide a versatile welding apparatus. Last but not least,the tip design should be symmetrical with respect to the longitudinalaxis of the resonator to exhibit a dynamically balanced condition andhence avoid undesirable modes of vibration of the resonator, that islongitudinal vibration and not flexural mode of vibration.

BRIEF SUMMARY OF THE INVENTION The tip construction disclosed hereafterovercomes the above described shortcomings of the prior art and fulfillssubstantially all of the desirable characteristics listed heretofore. Tothis end, the tip is a sleeve adapted to be mounted to an antinodalregion of the resonator. The tip has two plane'end faces for'being urgedinto abutting contact with a complementary end face of the horn, usingscrew means to exert the engagement pressure. A set of equidistantlyspaced ridges extend in a radial direction from the body of the sleeveand each such ridge is provided with a respective peripherally disposedworkpiece engaging surface. The plurality of workpiece engaging surfacescan be used in sequence as one or more of the surfaces indicates wearand is no longer useful.

Several other characteristics of this new design are important inassessing the advance provided in the art. The clamping areas of the tipdisclosed herein are flat and therefore are easy to manufacture and arereadily mated with complementary surfaces. Uniform clamping pressure canbe provided over a large area so as to reduce stress concentration andwear. The clamping area is large in relation to the workpiece engagingsurface, typically being 2 to 20, and the clamping is achieved in asecure manner even for large workpiece engaging surfaces, hence wear isminimal. The tip design is symmetrical and dynamically balanced withrespect to the resonator axis. The orientation of the workpiece engagingsurface is completely independent of the radial orientation of theresonator. Thesleeve configuration provides for multiple workpieceengaging surfaces which may be used in sequence providing enhanced lifefor the tip. Replacement and alignment of the tip is easy and can beaccomplished by unskilled personnel in a minimum of time. Mostimportantly, the thread used in attaching the tip to the resonator andproviding the engagement force is utilized when performing work in thedirection in which it exhibits maximum strength, that is, the axis ofthe thread and the axis of mechanical vibration imparted to theworkpiece are parallel instead of being perpendicular to one another.

Further and still other beneficial traits of the present design will beapparent from the following description when taken in conjunction withthe accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a side elevational view of atypical prior art arrangement;

FIG. 2 is an exploded view of certain portions of the arrangement shownin FIG. 1;

FIG. 3 is a side elevational view of the improved apparatus; 7

FIG. 4 is an enlarged view of the frontal portion of the resonator andwelding tip shown in FIG. 3;

FIG. 5 is an exploded view disclosing the welding tip and its attachmentto the resonator, and

FIG. 6 is a plan view of the welding tip along line 6-6 in FIG. 5.

DESCRIPTION OF PRIOR ART Referring now to the figures and FIGS. 1 and 2in particular, a vibratory welding apparatus as described in the patentapplication supra is shown. A base 10 supports an elongated resonator.also called horn, made of two parts 12 and 14 which are acousticallycoupled to each other. Two flat support members 16 and 18, adapted toyield in the direction of longitudinal motion of the resonator, supportthe resonator in fixed position above the support 10. The supportmembers 16 and 18 engage the resonator l2 and 14 substantially at two ofits antinodal regions of longitudinal vibration.

The resonator made of metal, such as aluminum or titanium. ismechanically coupled to an electroacoustic converter unit 20 which isconnected to receive high frequency electrical energy, for instance at10 tt s ang sctriq ner 22 a iFi The converter unit by means ofpiezoelectric or magnetostrictive means (not shown) converts the appliedelectrical energy to mechanical vibrations which are applied to theresonator, causing the latter to be resonant at its predeterminedfrequency. A converter means suitable for the present purpose isdisclosed, for instance, in US. Pat. No. 3,328,610 dated June 27, I967,S. E. .lacke et al., entitled Sonic Wave Generator,", and the design ofresonators is described in Ultrasonic Engineering (book) by Julian R.Frederick, John Wiley & Sons, Inc., New York, N.Y. (196 pp. 8711) 103The resonator portion 14 is provided with a reduction in cross-sectionas indicated by numeral for causing increased mechanical amplitude ofvibration manifest at the end surface 32 which is disposed substantiallyat another antinodal region of longitudinal motion. The latter antinodalregion of the resonator is fitted with a welding tip 34 which by meansof a threaded stud 36 is assembled into a threaded, radially disposed,hole 38 of the resonator. The welding tip 34 has a workpiece engagingsurface 40 for contacting a workpiece W which with its uppermost side isurged into forced contact with the tip 34 by a hydraulic ram 42.

When the converter unit 20 is energized, the tip 34.

tip 34 will be subjected to wear as the result of its forced engagementwith the workpiece and the vibrations applied and, hence, the tip needsto be replaced periodically. Moreover, since the thread axis is disposedperpendicular to the axis of vibratory motion the thread supporting thetip is stressed in a sideways direction, force being appliedalternatingly from one side and then from the other. Additionally, thescrew attachment does not lend itself to provide predeterminedorientation of the surface 40 relative to the direction of vibrationeffected upon the workpiece. Also, as stated heretofore, the tipconfiguration and its attachment to the resonator cause a dynamicallyunbalanced condition for the resonator and are afflicted, still further,with the shortcomings previously recited.

DESCRIPTION OF PREFERRED EMBODIMENT OF INVENTION A preferred embodimentof the present invention is disclosed in FIGS. 3 to 6. Itemscorresponding to those previously described in conjunction with FIGS. 1and 2 are identified by identical reference numerals. The frontalportion 14' of the resonator is of cylindrical cross-section with areduction of cross-section occurring at 30. The frontal end oftheresonator is constructed to exhibit a flat radially disposed annularsurface 50, FIG. 5, from which a stud 52 provided with a male thread 54extends. Between the surface 50 and the threaded portion 54 of thestudthere is disposed a cylindrical shoulder 56.

The welding tip 60 is a substantially cylindrical sleeve and comprises asleeve body 62, FIG. 6, having a centrally disposed aperture 64dimensioned to snugly fit over the shoulder 56 of the stud 52. Threeequidistantly spaced discrete ridges 66 extend radially outward from thebody 62 and each ridge 66, forming a unitary part of the body, exhibitsa respective peripherally disposed workpiece engaging surface 68. Thetip 60 is assembled upon the resonator by sliding it with its aperture64 over the shoulder 56 and then threading the internally threaded nut70, having an integral flanged portion 72, upon the thread 54. Whiletightening the nut upon the stud, one of the workpiece engaging surfaces68 is manually oriented by rotation until it is in the desired workpieceengaging position. Tightening the nut 70 forces the face 74 of thewelding tip 60 into abutting engagement with the radial surface 50, andthe other parallel face 76 of the welding tip into engagement with theradial surface 78 of the nut 70.

If wear occurs at the selected workpiece engaging surface 68, the nut 70is loosened and the top 60 is rotated until the next workpiece engagingsurface 68 is suitably indexed relative to the workpiece W. While threeworkpiece engaging surfaces 68 have been shown it will be apparent thattwo, four or more of such surfaces may be providedv If the ridges 66 areequidistantly spaced and of equal configuration, the tip 60 isdynamically balanced. Moreover, the welding tip represents only arelatively small mass in relation to the mete s mbl ty i .1221 11.1 qa nway affects the dynamic condition of the resonator.

It should be noted, moreover, that the thread 54, as contrasted with theprior design, is stressed in the direction in which it exhibits maximumstrength. Specifically, the thread axis and the direction of vibrationof the workpiece engaging surface of the welding tip relative to theworkpiece are parallel with each other. This condition eliminates thesideways thrust experienced heretofore. Furthermore, the welding tip canbe oriented radially at any angle and in a completely inde pendentmanner, that is, orientation of the resonator is not affected. Inaddition, the desired characteristics enumerated in part heretofore aremet by this relatively simple and inexpensive welding tip design.

It will be apparent, furthermore, that the workpiece engaging surfaces68 can be shaped to assume the particular contour of the workpiece. Forinstance, the workpiece engaging surfaces do not need to be flat orcurved, but may be grooved to receive a wire, or contoured in otherconfigurations as dictated by the workpiece portion to be contacted.

While the welding tip 60 has been described herein as being of sleeveconfiguration, it will be obvious to those skilled in the art that ifthe workpiece engaging surface is shorter, the sleeve may be shortenedas well, assuming a ring or washer-like configuration. These latterconstructions as used herein shall be comprehended a by the term sleeve.

What is claimed is:

1. In a vibratory welding apparatus the combination of:

an elongated resonator dimensioned to be resonant along its longitudinalaxis at a predetermined frequency of vibration having two ends;

means coupled to said resonator at one end thereof for impartingvibrations of said predetermined frequency to said resonator and causingsaid resonator when resonant to exhibit at least two antinodal regionsand one nodal region of longitudinal vibration;

a replaceable welding tip in the form ofa sleeve having two radiallydisposed end faces, said sleeve having a mass not exceeding onetwenty-fifth of that of said resonator;

screw means detachably clamping one of said faces of said sleeve inabutting engagement with a complementary radial surface disposedsubstantially at the other end of said resonator, and

a ridge forming a unitary part of said sleeve radially extending fromsaid sleeve and provided with a peripheral workpiece engaging surfaceadapted to impart vibratory energy to a workpiece in forced contact withsaid peripheral surface, the axis of vibration of said workpieceengaging surface relative to the workpiece responsive to said resonatorbeing resonant being substantially parallel to the thread axis of saidscrew means.

2. In a vibratory welding apparatus as set forth in claim I, a pluralityof ridges extending from said sleeve, each ridge having a respectiveperipheral workpiece engaging surface.

3. In a vibratory welding apparatus as set forth in claim 2, saidplurality of ridges being equidistantly spaced about the center of saidsleeve and being of substantially identical configuration for exhibitinga dynamically balanced condition to said resonator.

4. In a vibratory welding apparatus as set forth in claim 2, said screwmeans comprising an internally threaded nut mating with a threaded studextending from the other end of said resonator.

5. In a vibratory welding apparatus as set forth in claim 2, the otherend of that resonator being disposed substantially at an antinodalregion of longitudinal vibration.

6. In a vibratory welding apparatus as set forth in claim 2, the otherend of said resonator being located substantially at an antinodal regionof said resonator and including a shoulder and-a threaded stud extendingfrom the other end, said sleeve having a centrally disposed aperturedimensioned to snugly slide over said shoulder.

7. In a vibratory welding apparatus as set forth in claim 6, saidradially disposed faces being disposed in parallel planes, and saidscrew means engaging the other one of said faces. I

8. In a vibratory welding apparatus as set forth in claim 2, saidresonator being dimensioned for being resonant at a frequency in therange between 5 and KHZ.

9. In a vibratory welding apparatus the combination of:

an elongated resonator dimensioned to be resonant along its longitudinalaxis at a predetermined frequency of vibration having two ends;

electro-acoustic transducer means coupled to said resonator at one endthereof for imparting vibrations of said predetermined frequency to saidresonator and causing said resonator when resonant to exhibit at leasttwo antinodal regions and one nodal region of longitudinal vibration;

support means coupled to said resonator for supporting said resonatorand transducer means in stationary position;

a replaceable welding tip in the form of a sleeve having two radiallydisposed end faces said sleeve having a mass not exceeding onetwenty-fifth of the mass of resonator;

screw means detachably clamping one of said faces of said sleeve inabutting contact with a complementary radial surface disposedsubstantially at the other end of said resonator;

a plurality of discrete ridges forming a unitary part of said sleeveradially extending from said sleeve, each ridge provided with arespective peripherally disposed workpiece engaging surface adapted toimpart vibratory energy to a workpiece in forced contact therewith, thedirection of vibration of said workpiece engaging surface responsive tosaid resonator being resonant being substantially parallel to the threadaxis of said screw means, and

said screw means mounting and clamping said sleeve in such a manner thatresponsive to indexing said sleeve relative to said other end a selectedone of said peripherally disposed surfaces is mounted for engaging aworkpiece.

10. In a vibratory welding apparatus as set forth in claim 9, the otherend of said resonator being disposed substantially at an antinodalregion of longitudinal vibration.

11. In a vibratory welding apparatus as set forth in claim 10, the otherend of said resonator including a shoulder and a threaded stud extendingtherefrom, said sleeve having a central aperture dimensioned forslidably fitting over said shoulder, and said screw means including athreaded nut adapted to mate with said stud and upon being tightenedclamping said sleeve with its face in said abutting contact.

#lf l

1. In a vibratory welding apparatus the combination of: an elongatedresonator dimensioned to be resonant along its longitudinal axis at apredetermined frequency of vibration having two ends; means coupled tosaid resonator at one end thereof for imparting vibrations of saidpredetermined frequency to said resonator and causing said resonatorwhen resonant to exhibit at least two antinodal regions and one nodalregion of longitudinal vibration; a replaceable welding tip in the formof a sleeve having two radially disposed end faces, said sleeve having amass not exceeding one twenty-fifth of that of said resonator; screwmeans detachably clamping one of said faces of said sleeve in abuttingengagement with a complementary radial surface disposed substantially atthe other end of said resonator, and a ridge forming a unitary part ofsaid sleeve radially extending from said sleeve and provided with aperipheral workpiece engaging surface adapted to impart vibratory energyto a workpiece in forced contact with said peripheral surface, the axisof vibration of said workpiece engaging surface relative to theworkpiece responsive to said resonator being resonant beingsubstantially parallel to the thread axis of said screw means.
 2. In avibratory welding apparatus as set forth in claim 1, a plurality ofridges extending from said sleeve, each ridge having a respectiveperipheral workpiece engaging surface.
 3. In a vibratory weldingapparatus as set forth in claim 2, said plurality of ridges beingequidistantly spaced about the center of said sleeve and being ofsubstantially identical configuration for exhibiting a dynamicallybalanced condition to said resonator.
 4. In a vibratory weldingapparatus as set forth in claim 2, said screw means comprising aninternally threaded nut mating with a threaded stud extending from theother end of said resonator.
 5. In a vibratory welding apparatus as setforth in claim 2, the other end of that resonator being disposedsubstantially at an antinodal region of longitudinal vibration.
 6. In avibratory welding apparatus as set forth in claim 2, the other end ofsaid resonator being located substantially at an antinodal region ofsaid resonator and including a shoulder and a threaded stud extendingfrom the other end, said sleeve having a centrally disposed aperturedimensioned to snugly slide over said shoulder.
 7. In a vibratorywelding apparatus as set forth in claim 6, said radially disposed facesbeing disposed in parallel planes, and said screw means engaging theother one of said faces.
 8. In a vibratory welding apparatus as setforth in claim 2, said resonator being dimensioned for being resonant ata frequency in the range between 5 and 100 KHz.
 9. In a vibratorywelding apparatus the combination of: an elongated resonator dimensionedto be resonant along its longitudinal axis at a predetermined frequencyof vibration having two ends; electro-acoustic transducer means coupledto said resonator at one end thereof for imparting vibrations of saidpredetermined frequency to said resonator and causing said resonatorwhen resonant to exhibit at least two antinodal regions and one nodalregion of longitudinal vibration; support means coupled to saidresonator for supporting said resonator and transducer means instationary position; a replaceable welding tip in the form of a sleevehaving two radially disposed end faces said sleeve having a mass notexceeding one twenty-fifth of the mass of resonator; screw meansdetachably clamping one of said faces of said sleeve in abutting contactwith a complementary radial surface disposed substantially at the otherend of said resonator; a plurality of discrete ridges forming a unitarypart of said sleeve radially extending from said sleeve, each ridgeprovided with a respective peripherally disposed workpiece engagingsurface adapted to impart vibratory energy to a workpiece in forcedcontact therewith, the direction of vibration of said workpiece engagingsurface responsive to said resonator being resonant being substantiallyparallel to the thread axis of said screw means, and said screw meansmounting and clamping sAid sleeve in such a manner that responsive toindexing said sleeve relative to said other end a selected one of saidperipherally disposed surfaces is mounted for engaging a workpiece. 10.In a vibratory welding apparatus as set forth in claim 9, the other endof said resonator being disposed substantially at an antinodal region oflongitudinal vibration.
 11. In a vibratory welding apparatus as setforth in claim 10, the other end of said resonator including a shoulderand a threaded stud extending therefrom, said sleeve having a centralaperture dimensioned for slidably fitting over said shoulder, and saidscrew means including a threaded nut adapted to mate with said stud andupon being tightened clamping said sleeve with its face in said abuttingcontact.